Electrode assembly



y 0, 1949. G. v. CALABRESE 2,470,066

ELECTRODE ASSEMBLY Filed March 30, 1946 Patented May 10, 1949 UNITEDSTATES PATENT OFFICE ELECTRODE ASSEMBLY George V. Calabrese, Chicago,Ill., assignor to Lumenite Electronic Company, Chicago, 111., acorporation of Illinois Application March 30, 1946, Serial No. 658,399

4 Claims. 1

This invention relates to improvements in electrode assemblies for usein conjunction with signalling or control circuits.

In numerous industries it is desirable, in carrying out manufacturing orliquid treating operations, to maintain the level of liquids in tanks orother containers within predetermined limits. For example, in the dairyindustry, milk often is directed into tanks for certain treatments andduring which it is desirable to maintain the level between particularlimits. In some such treatments, foam tends to form which it is likewisedesirable to hold below limits. The present improvements relate to anelectrode assembly, comprising one to three or more electrodes ofselected length that project into the tank each for contact with theliquid or foam when at a predetermined level for efiectuating actuationor deactuation of a control or signalling system. Thus when theimprovements are employed in a signalling system, the rise or fall of aliquid to certain levels will energize or deenergize suitable signalsand where the electrode assembly is employed in conjunction with acontrol system, the rise or fall of the liquid to levels determined bythe particular electrodes employed will deenergize or energizerespectively control-valve actuating means or a pump motor, for example,which regulates the supply of additional fluid to the tank in question.Ordinarily for mere upper and lower level control, a two electrodeassembly is employed. However, two control electrodes may be combined,in the same assembly, with a third electrode which may be a part of asignal system whereby upon the arising of a certain condition, as forexample, the formation of and rise of foam to a certain level, a signalwill be actuated at an attendants station. Variations in the number ofelectrodes in a particular electrode assembly of the improved type maythus be employed as conditions under which the assembly is used and thefunctions to be performed by the electrodes may require.

One object of the invention is to provide an electrode assemblycomprising one or more electrodes which are adapted to be supportedremovably in position within a tank, vat or the like, and which assemblynot only provides desirable electrical insulation for the electrode orelectrodes but also provides a sanitary mounting for the same.

Another object of the invention is to provide an assembly comprisingplural electrodes which may be of similar cross sectional area but whichare provided with external terminals adapted for use with a suitablejack or electrical contact plug which can be connected to the terminalsonly in the proper relation thereby insuring the correct electricalhook-up of the respective electrodes in the intended signal or controlcircuits.

Another object of the invention is to provide an electrode assemblycomprising an electrical insulating disc-like support for one or moreelectrodes and which is adapted to be removably clamped in position by apair of coacting threaded members and to provide a sanitaryselfcentering and self-aligning gasket or sealing member between saidmembers.

Other objects of the invention relate to various features ofconstruction and arrangements of parts which will be apparent from aconsideration of the following specification and accompanying drawings,wherein Fig. 1 is a broken sectional view of a tank having the improvedelectrode assembly mounted thereon, a cooperating jack being showndetached from the jack terminals.

Fig. 2 is a top plan view taken on line 2-2 of Fig. 1.

Fig. 3 is a side elevational view of an insulating disc of the electrodeassembly which is provided with three electrodes.

Fig. 4 is a similar view illustrating a single electrode.

In the drawing, Ill indicates a tank for holding a liquid H, the levelof which is to be maintained within certain limits such as a lower limitindicated by line l2 and an upper limit indicated by line l3 whichcorresponds to the surface of the liquid ll shown in the tank. Theelectrode assembly comprises a base I4 of tubular form, the lower end ofwhich is adapted to be secured within an opening in a tank as by weldingas indicated at IS. The upper portion of the base is externally threadedas indicated at l6, said upper portion being shown in Fig. 1 as somewhatthicker than the lower portion. The upper edge of the base 14constitutes a seat I! of inverted frusto-conical form.

A disc-like member I8 of insulating material is provided having afrusto-conical surface I9 at its lower edge and is arranged to bepositioned upon the seat ll of the base M. The member 18 preferably isformed of a suitable insulating plastic which will not affect the tasteor odor of the liquid such, as milk, within the tank. The upper marginof the disc I8 is rabbeted to form a shoulder 20. A tubular clampingmember 2! which, as shown in Fig. 2 has an outer hexagonal surface, isinternally threaded as indicated at 23 for coaction with the threads isof the base M. The upper portion of the clamping member 2| is providedwith an inwardly directed flange 24 which extends inwardly sulficientlyfor engagement with the shoulder of the disc l8 whereby as the clampingmember is screwed downwardly upon the base, with the disc i8 resting onthe latter, the disc is pressed into sealing contact with the base byreason of the mating conical surfaces above described. By reason of themating conical surfaces, the disc is selfcentering as it is presseddownwardly by the clamping member as will be seen. The flange 24, whichis of an internal diameter slightly greater than the diameter of thevertical wall of the annular rabbet, cooperates with said vertical wallin effecting the centering and alignment of the disc within theassembly.

The disc [8 is provided with one or more passages therethrough,depending upon the number of electrodes to be provided in thatparticular disc. In Fig. 1 the disc is shown provided with twoelectrodes 25 and 26 which preferably areformed. of rods of stainlesssteel. Other material, depending upon the use to which the assembly isto be put, may be employed. The electrode or electrodes are fixed withinthe passages provided therefor in the disc is for preventing relativesliding movement of the electrodes through the disc as a jack is pressedinto engagement with or removed from the ends of the electrodesprojecting outwardly from the disc. The projecting ends 25a and 26a ofFig. 1 constitute jack terminals for electrical connection with a-suitable jack such as is indicated by numeral 2! whereby the electrodescan be connected conveniently in proper electrical signalling or controlcircuits. As shown in Fig. l, the terminals 25a and 26a are of differentdiameters which; precludes connecting the terminals improperly with ajack by reason of the fact that the jack 2? as shown in Fig. 1, hasterminal receiving sockets 28 and 29 which are of correlative diametersfor receiving respectively the terminals 250; and 25a,

shown in the drawings, each of the electrodes is provided with aninsulating sheath til. The sheath may be molded or cast directly uponthe electrode or it may be formed of tubular material having passages ofa diameter for snugly embracing the respective electrode. Where it ispre formed and assembled upon the electrode, it preferably is ofsubstantial length and suitable adhesive is used for insuringnon-slipping relation between the sheath and the electrode. As shown inFig. 1, the passages formed in the disc 3-. for receiving the electrodesare enlarged at their lower portions for receiving the upper ends of therespective sheaths til. Within the enlarged portions of the passagesadhesive 3i may be employed to insure a secure bond between the sheathsand the disc thereb securing the electrodes against axial movementrelative to the disc.

Where two electrodes are employed for maintaining the level of a liquidbetween predetermined limits, the electrodes are of the lengths requiredin the particular installation. As shown in Fig 1, the shorter electrodeis in contact with the upper surface of the liquid shown in the tankwhile the longer electrode extends to a level which may be assumed to bethe lower level to Whichthe liquid may be permitted to fall. Theconductors 32 and 33 extending from the jack 21, are connected tosuitable known control means, not herein disclosed, whereby upon thefall of the liquid to the level of line I2, a pump or valve or the likewil be actuated to raise the level of the liquid to the upper level !3whereupon the contact of the liquid with the shorter electrode 25 willarrest inward how of the fluid to the tank. The particular control meansreferred to is known and forms no part per se or" the presentimprovements.

The electrode assembly above described affords an airtight seal of theopening provided in the tank for the electrodes. The assembly also issanitary and permits the removal of the electrodes, when desired, by themere removal of the clamping member 25 which enables the disc and theassociated electrodes to be lifted from operative position forcleansing, sterilizing, or the like.

My electrode assembly may be used to especial advantage with a circuitfor controlling the level of a liquid having a relatively low electricalconductivity, such as milk. That is, in such a system employing, forexample, a double electrode assembly as illustrated in Fig. l, the tinycurrent capable of passing through the liquid into the electrodes isdirected to the input or controlling portion of the control circuit, theoutput portion of which, in turn, controls the passage of a much largercurrent to a pump motor to start the motor when the fluid level dropsbelow the bottom electrode and to stop it when the level rises to theupper electrode.

Liquid food products such as milk are not very conductive and thereforethe control circuit must be responsive to current how in the inputthereof (that is, through the milk to the electrodes) in the order ofabout /iou,ooo ampere at less than volt.

Many of these food products foam easily and therefore the entireinterior of the vessel including the area around the electrodes isnormally covered with a film of somewhat conductive liquid or foam layereven when the vessel is nearly empty. Milk is particularly subject tofoaming, especially at the warm pasteurizing temperatures encountered inthe dairy industry.

A difiilculty which I have found, in working with circuits responsive tosuch small currents, and with foaming liquids, is that the foam itselfor the fluid layer around the electrodes resulting from the foam issufficiently conductive so that, without an insulating sheath such as30, the foam or layer itself would conduct sufiicient current betweenone or both of the two electrodes and the grounded housing to cause thecontrol circuit to indicate that the vessel is full or nearly full whenactually it might be nearly empty. I have discovered, however, that byfitting each electrode with a fluid-tight insulating sheath, I canextend the linear distance between bare portions of the electrodes andthe vessel so the increased electrical path along the foam or fluidlayer surfaces would have such a high resistance that it would notconduct a current high enough to falsely actuate the pump circuit.

As an illustration of the extreme sensitivity of a control circuit withwhich my electrode assembly is intended to be used, under somecircumstances a person can cause the circuit to indicate full andthereby stop the pump merely by placing a hand on one of the electrodes.

By using the insulating sheathing on at least one and preferabl on allof the electrodes, I have been able to make the control circuit re-.sponsive to very tiny currents, independent of false actuations causedby response to stray currents conducted by the foam or fluid layer, andtherefore have made it possible to control maximum and minimum fluidlevels to within /100 inch. The expedient of employing the sheathing 30on the electrodes renders the foam layer on the internal surfacesineffective to conduct a current sufficient to interfere with properfunctioning of the circuit, by causing the bare surfaces of theelectrodes to be separated from one another by a longer, and thereforemore resistant, path. The only other alternative would be to use anelectrode assembly having an impractically large diameter. It will beapparent that the insulating sheaths 30 may be molded as an integralpart of the disc l8 where desired.

In Fig. 4, as above stated, a single electrode indicated by numeral 33is shown supported by the disc 34. The disc 34 although shown on asmaller scale than the disc l8, in shape and size may correspond to thedisc !8 except that it is provided with a single molded boss 35 throughwhich the electrode extends rather than two molded bosses 36 as shown inFig. 1. The bosses mentioned afford longer electrode passages within thedisc and therefore provide a firmer mounting of the electrodes withinthe discs.

In Fig. 3, three electrodes are shown sup ported by a disc 31 which maycorrespond in shape and size to the disc [8. Where three electrodes areemployed they are spaced preferably at 120 of arc although they may beotherwise arranged if desired. A three electrode assembly is useful inconjunction, for example, with liquids which tend to foam. The twolonger electrodes 38 and 39 of Fig. 3 may be used in a control systemcorresponding to that described above in conjunction with electrodes 25and 26 in Fig. 1. The shorter electrode 40 may function for initiatingthe operation of a signal system upon the rise of foam to the level ofthe lower end of electrode 49 thus warning an attendant of an excessformation of foam in the liquid. Other uses of the assembly are Withinthe ambit of the invention.

In Fig. 3, jack terminals 38a, 39a and 40a are shown as being ofdifferent diameters for use with a jack constructed in accordance withthe principle of jack 2! for affecting connection of the electrodes inproper circuits.

While certain uses of the assemblies have been mentioned, it will beapparent that other uses may be found for the improvements. Variationsin the particular structure described may also be resorted to within thespirit of the present improvements.

I claim:

1. An electrode assembly comprising a base provided with an axialpassage and having exterior threads on the upper portion and a lowerdepending skirt adapted to be secured within an opening in a tank wall,the outer end of said base providing a seating surface of invertedfrusto-conical form, an electrode supporting member comprising anelectrical insulating disc having a marginal wall on the lower sidethereof of frusto-conical form adapted to seat on and provideself-centering sealing contact with said seating surface of said basemember and to cooperate with said seating surface to effect disposal ofsaid disc in a plane normal to the axis of said passage, an electrodesupported by said disc and extending through the same and through thepassage of said base for contact at the inner end with a fluid in thetank and provided with a jack terminal at the outer end, said electrodehavin an insulating sheath secured to the outside thereof in fluidtightrelationship on the underside of the disc, and a cylindrical clampingmember having an axial passage therethrough and having an internallythreaded lower portion adapted for coaction with the exterior threads ofsaid base and having a flange at the outer end extending inwardly forengagement with a marginal portion of said disc for clamping the samefirmly between said member and base with the conical walls of the baseand disc in sealing contact with the electrode terminal projectingoutwardly through said clamping member.

2. An electrode assembly comprising a cylindrical base provided with anaxial passage therethrough and having exterior threads on the upperportion and a lower depending portion of reduced diameter adapted to befixed in position within an opening in a tank wall, the outer end ofsaid base having a seating surface of inverted frustoconical form, anelectrode supporting member comprising an electrical insulating dischaving a marginal sealing wall on the lower side thereof offrusto-conical form adapted to seat upon said seating surface of saidbase, a cylindrical clamping member having an axial passage through thesame and provided with internal threads in the lower portion forcoaction with the external threads of said base and provided with aninwardly directed upper flange adapted to engage an upper marginalportion of said disc for clamping the same in centered relation uponsaid base with the respective seatin walls thereof in sealing contact,and a rod-shaped electrode secured to said dis-c and extending throughthe same and through the passages of said base and clamping member andprovided at the outer end with a jack terminal for enabling theelectrode to be connected into an electrical circuit, said electrodehaving a fluid-tight insulating sheath extending therealong on theunderside of said disc for a distance from the latter.

3. An assembly for supporting a rod-shaped electrode comprisin aninsulating disc provided with a boss formed on the upper surface thereofand an electrode receiving passage extending through said disc and boss,the portion of the passage in the disc being of greater diameter thanthe portion extending through said boss, a rodlike electrode extendingthrough said passage and provided with an insulating sheath adhered tothe outside thereof and secured at the upper end in said enlargedportion of said passage for retaining the electrode in fixed positionwith respect to said disc and for preventing the leakage of fluid upwardalong said electrode, the upper end of the electrode above said discconstituting a jack terminal whereby the electrode is readilyconnectable in an electrical circuit, a tubular base member adapted tobe secured in an opening in a tank wall and having an outer edge uponwhich a lower peripheral portion of said disc is adapted to seat, and aclamping member arranged for coaction with said base for engaging anupper peripheral portion of said disc for clampin the disc against saidouter edge of said tubular base to seal the passage thereof and tosupport the electrode in fixed position.

4. An electrode assembly comprising a tubular base having exteriorthreads on the upper portion thereof and adapted for insertion at thelower end in an opening of a receptacle for securement therein, theouter edge of said base being of inverted frusto-conical form, anelectrical insulating discv provided with a lower peripheral surfacemating said outer edge of said base and providing self-centering sealingContact with said edge, a plurality of rod shaped electrodes extendingin axial directions through said disc and being spaced radially inwardlyof said mating surface and spaced also from contact with the interiorwall of said tubular base, each of said electrodes having an individualinsulating sheath extending therealong in fluid-tight relationship for adistance from the underside of said disc, said disc being rabbeted atthe outer edge to provide a clamp. engaging ledge, and a tubular clampmemher having internal threads in the lower portion for coaction withthe external threads of said base and an inwardly extending annularshoulder at theouter end of an internal diameter for engagement withsaid ledge of said disc for pressing saidmating surfaces of said discand base into cooperative sealing contact and maintaining saidelectrodes in fixed relation within the assembly.

GEORGE V. CALABRESE,

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 276,415 Hurlbut Apr. '24, 18831,159,869 Sakai Nov. '9, 11915v 1,398,270 Nickum Nov. 29, 1921 1,594,814Brodin et a1 Aug. 3, 1926 1,683,362 Lofiler Sept. 4, 1928 1,807,781 EddyJune 2, 1931 2,073,268 Ray Mar. .9, 1937 2,083,916 Mascuch June 15,11937 2,26%816 Treanor Dec. .2, 1941 2,329,961 Walker Sept. 2.1,, 19.432,361,215 Lamberger et a1. Oct. 24, 1944 2,400,364 Mittermaier May 14,1946.

FOREIGN PATENTS Number Country Date 375,877 Germany May 19, 1923

